The devices described below are intended for treatment of defects in the cerebral arteries and veins. Defects of the cerebral arteries include aneurysms, fusiform aneurysms, arteriovenous malformations, arteriovenous fistulas, cavernous fistulas and dissections and other hyper-vascular lesions (head and neck tumors, etc.). These defects cause of variety of symptoms, ranging from headache and vision loss to stroke and death. Preferably, these defects would be treated with devices and techniques that leave the associated parent artery or vein intact and patent so that it may continue to supply blood to regions of the brain which it naturally supplies. Such techniques include filling an aneurysm with occlusive polymers or occlusive coils, or inserting stents or covered stents, where feasible. In many cases, however, this is not advisable or possible because the artery vein segment in which the defect, or the defect itself, will not accommodate the devices, or because the patient's condition indicates that immediate cessation of blood flow is required.
The alternate, when parent artery preservation is not advisable, is parent artery occlusion, or PAO. Parent artery occlusion is accomplished by quickly and securely closing off a length of a blood vessel near the defect, and preferably results in immediate and complete blockage of blood flow to the defect, and permanent isolation of the blood vessel segment near the defect. Parent artery occlusion is sometimes referred to more broadly as parent vessel occlusion, to encompass occlusion of both arteries and veins. Several endovascular devices and techniques have been developed to accomplish parent artery occlusion. Detachable balloons have previously been proposed and used for parent artery occlusion, but were not successful because the balloons to often leaked and deflated, leading to major embolic complications. (Giant Intracranial Aneurysms at 257 (Awad, Issam and Barrow, Daniel, eds., Thieme/AANS 1st ed., 1995)). Occlusive coils have been used to pack fusiform aneurysms and cavernous fistulas, but this is extremely expensive (it may require dozens of coils) and does not result in immediate occlusion. Thus, trickling blood flow, which occurs for several minutes while the patient's blood is coagulating around the mass of coils, may lead to creation and migration of thrombus from the mass of coils. Vascular plugs have been used to accomplish parent artery occlusion. Currently available plugs, such as the Amplatzer vascular plug, are used off-label in the neuro-vasculature, and are difficult to deploy. Ross, et al., The Vascular Plug: A New Device for Parent Artery Occlusion, 28 AJNR Am J Neuroradiology 385 (February 2007). Also, the open-mesh construction of these vascular plugs may result in dislodgement of thrombus as it is forming on the plug, leading to embolization downstream of the occluded artery.